feat(map): run the Match query before navigating to the mutual page

Tapping the grid-QSO dialog "Match" button now starts the pass query on
the map page and only navigates to the match page once it finishes, so the
page's first frame already contains the results — the time-range card at
the top and the pass curves right below, with no scroll flicker. The dialog
button shows a spinner and is disabled while calculating. A uiState
collector in MainScreen performs the actual navigation (still a push, so
the back gesture returns to the map). Failures/exceptions still navigate so
the user is never stuck on the map page.

app/src/main/java/com/rtbishop/look4sat/MainScreen.kt

@@ -177,6 +177,28 @@ fun MainScreen(
         factory = MapFilterViewModel.factory()
     )
 
+    // Map grid-QSO dialog "Match" button: pre-fill the match page for that
+    // grid and run the query BEFORE navigating, so the page's first frame
+    // already contains the results (time-range card at the top, pass curves
+    // right below — no scroll flicker). Navigation happens once the query
+    // finishes (see the collector below).
+    val mutualState by mutualViewModel.uiState.collectAsStateWithLifecycle()
+    val matchCalculating = mutualState.pendingNavigation && mutualState.isCalculating
+
+    LaunchedEffect(mutualViewModel) {
+        mutualViewModel.uiState.collect { state ->
+            if (state.pendingNavigation && !state.isCalculating) {
+                mutualViewModel.consumePendingNavigation()
+                // Push Mutual on top of the Map entry instead of replacing the
+                // stack (bottom-nav style): the system back gesture then pops
+                // back to the map page, which is the page the user came from.
+                if (backStack.lastOrNull() !is Screen.Mutual) {
+                    backStack.add(Screen.Mutual)
+                }
+            }
+        }
+    }
+
     CompositionLocalProvider(
         LocalElevationThresholds provides ElevationThresholds(
             low = otherSettings.lowElevation,
@@ -246,17 +268,14 @@ fun MainScreen(
                         entry<Screen.Map> {
                             MapDestination(
                                 mapFilterViewModel = mapFilterViewModel,
+                                matchCalculating = matchCalculating,
                                 onMatchGrid = { grid ->
-                                    // Grid-QSO dialog "Match" button: pre-fill the
-                                    // match page for that grid and open it.
+                                    // Grid-QSO dialog "Match" button: pre-fill
+                                    // the match page for that grid and start the
+                                    // query. Navigation to the match page is
+                                    // handled by the uiState collector above,
+                                    // once the query finishes.
                                     mutualViewModel.prefillMatchFromGrid(grid)
-                                    // Push Mutual on top of the Map entry instead of
-                                    // replacing the stack (bottom-nav style): the
-                                    // system back gesture then pops back to the map
-                                    // page, which is the page the user came from.
-                                    if (backStack.lastOrNull() !is Screen.Mutual) {
-                                        backStack.add(Screen.Mutual)
-                                    }
                                 }
                             )
                         }